dc.description.abstract | Slope disasters have received attention in recent year worldwide and in Taiwan, because of extremely heavy rainfall presumed to relate to climate change. For the purpose of landslide research and geological sensitive zone designation, we require division of appropriate slope units for building up various types of landslide potential evaluation system. In this study, one of a small catchment in the Tahan river watershed was chosen as the training area, using an object-oriented classification method to automatically generate slope-units. I used DTM (Digital Terrain Model) as raw data to produce raster data layers which include slope gradient, slope aspect, curvature, drainage system, catchment area. These raster data were imported into an object-oriented analysis software, which was known as Definiens, weight of each data layer was given, and then segmentation as well as slope-unit generation was executed, according to the heterogeneity and spatial correlation of the imported data. After that we applied this rule in other catchments of the Tahan river watershed and viewed its effectiveness to make further amendments for a reasonable general rule. A standard deviation of slope aspects in each slope-unit was calculated for checking purpose. Finally, we used the slope aspect and the catchment area, as well as drainage system for segmentation through comparison of the results from different layer weightings. The final result of using this segmentation criteria satisfied the definition of slope-unit that high homogeneity within each unit and high heterogeneity between the neighbor units. It shows that each of a small catchment of a first-order stream could be divided into two or three or even more parts of slope units. This provides more detailed and reasonable result than previous studies.
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